There are many applications that call for a pump to be self-priming, i.e., where the level of liquid to be pumped is below the pump inlet. Typically, priming of a pump is accomplished utilizing a separate priming chamber and a vacuum pump, or the like, or when self-priming is accomplished normally a check valve is utilized at the foot of the suction line and/or in the pump itself, or an internal valve in a priming chamber.
According to the present invention, a self-priming type pump is provided that can be considerably smaller than conventional self-priming pumps, and/or can have a significantly shorter priming cycle time. The pump according to the invention also may be considered simplier than many conventional self-priming pumps, no valves being associated therewith. The pump according to the invention utilizes particular static components, and particular a cooperation between static components and rotating impeller, to effect separation of air from the liquid, and prevent return of separated air to the liquid inlet, or liquid recirculating ports.
The pump according to the invention includes a housing with an impeller mounted within the housing for rotation about an axis of rotation. Preferably, the pump comprises a centrifugal pump (that is, the liquid inlet is inline with the axis of rotation of the impeller, and the liquid outlet or outlets are radially spaced from, and in a dimension generally perpendicular to, the impeller axis of rotation), although in some embodiments the pump may comprise other types of impeller pumps, such as a rotary pump. Preferably, the axis of rotation of the impeller is generally horizontal, and a recirculating liquid reservoir is defined below the axis of rotation.
The housing includes means defining at least one, and preferably a plurality, of liquid recirculating ports below the axis of rotation of the impeller, and extending generally parallel to the axis of rotation. An air shield is provided on that portion of the housing adjacent an outlet below the axis of rotation, to prevent recirculating of air discharged through the outlet to the liquid recirculating ports. A drain hole is also provided in the housing at the bottom thereof, radially outwardly from the impeller.
The outlets from the housing are defined by diffusers, and each diffuser includes a peeler (sometimes known as a trimmer or a volute tongue) for effectively deflecting air bubbles out the discharge. At an outlet above the axis of rotation, a reversing deflector is associated with the outlet. The reversing deflector deflects the discharged liquid with entrained air so that it is essentially reversed in direction, and this deflection facilitates the separation of air entrained in the liquid from the liquid, the air having a tendency to then go upwardly and pass out of the system, while the liquid can pass to the recirculating liquid reservoir during the self-priming action.
Preferably, the impeller includes a front shroud at the portion thereof adjacent the inlet, the front shroud having a plurality of external vanes formed thereon. The vanes serve to facilitate separation of air from the liquid flowing into the inlet, and at the same time effect positive recirculating of liquid from the recirculating liquid reservoir through the recirculating ports.
It is the primary object of the present invention to provide a simple, efficient, and effective self-priming pump, particularly a self-priming centrifugal pump. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.